VM: Make use_osr an Isolate flag, similar to how we made use_field_guards.

runtime/vm/flow_graph_compiler.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 315 matching lines @@
   return FLAG_optimization_counter_threshold >= 0;
 }
 
 
 bool FlowGraphCompiler::CanOptimizeFunction() const {
   return CanOptimize() && !parsed_function().function().HasBreakpoint();
 }
 
 
 bool FlowGraphCompiler::CanOSRFunction() const {
-  return FLAG_use_osr & CanOptimizeFunction() && !is_optimizing();
+  return isolate()->use_osr() && CanOptimizeFunction() && !is_optimizing();
 }
 
 
 bool FlowGraphCompiler::ForceSlowPathForStackOverflow() const {
   if ((FLAG_stacktrace_every > 0) || (FLAG_deoptimize_every > 0) ||
       (isolate()->reload_every_n_stack_overflow_checks() > 0)) {
     return true;
   }
   if (FLAG_stacktrace_filter != NULL &&
       strstr(parsed_function().function().ToFullyQualifiedCString(),
@@ skipping 1539 matching lines @@
 
 
 void FlowGraphCompiler::FrameStateClear() {
   ASSERT(!is_optimizing());
   frame_state_.TruncateTo(0);
 }
 #endif  // defined(DEBUG) && !defined(TARGET_ARCH_DBC)
 
 
 }  // namespace dart